Apparatus for measuring molten metal levels in ladles



Jan. 24, 1967 R. BAILEY ETAL 3,299,705

APPARATUS FOR MEASURING MOLTEN METAL LEVELS IN LADLES Filed April 5,1964 INVENTORS Gilbert R. Bailey 8 United States Patent 3,299,706APPARATUS FOR MEASURING MOLTEN METAL LEVELS IN LADLES Gilbert R. Bailey,Ligonier, and Alex Simkovich, Latrobe,

Pa., assignors to Latrobe Steel Company, a corporation of PennsylvaniaFiled Apr. 3, 1964, Ser. No. 357,117 1 Claim. (Cl. 73304) This inventionrelates to methods and apparatus for measuring molten metal levels inladles and particularly to a method and apparatus for warning theapproach of slag toward the nozzle of the ladle so that slagcontamination of the last metal poured can be avoided.

A very real and long existing problem in the metal melting art has beenthe problem of determining when the slag on the metal in the ladle beingteemed was approaching the nozzle so that its issuance from the nozzlecould be avoided. Up until the present invention the determination ofthe position of the slag metal interface in the ladle was a matter ofpure conjecture and the last metal poured was invariably contaminatedwith slag, the amount of which was limited purely by the alertness andreflexes of the ladle man operating the ladle stopper.

We have invented a method and apparatus for measuring molten metallevels in ladles and eliminating the contamination of the last metalpoured by slag. Preferably we provide a ladle having a nozzle in thebottom thereof, stopper means movable in the ladle for opening andclosing said nozzle, means for moving said stopper means into and out ofsaid nozzle, a pair of conductor members extending into the ladle to apredetermined oint above the nozzle, an electrical circuit connectingsaid pair of conductor members, means for applying an electricalpotential to said circuit and signal means indicating a change in theelectrical characteristics of said circuit such as for example a changein electrical resistance. The conductor members may be a pair of rodsextending through the ladle sidewall, a single rod through the sidewalland the head of the stopper acting as a conductor or any of a variety ofother paired conductors within the scope of the claim hereafter setforth.

In the foregoing general statement we have set out certain objects,purposes and advantages of our invention. Other objects, purposes andadvantages will be apparent from a consideration of the followingdescription and the accompanying drawings in which,

FIGURE 1 is a schematic drawing of one embodiment of our invention; and

FIGURE 2 is a schematic drawing of a second embodiment of our invention.

Referring to FIGURE 1, we have illustrated a ladle 10, having arefractory lining 11. A nozzle 12 is provided in the bottom of ladle 10.The nozzle is opened and closed by a steel stopper rod 13 having aclay-graphite head 14 and surrounded by refractory sleeve 15. A stopperrod operating handle 16 of conventional form operates the stopper rod.An electrical lead 17 connects with the clay-graphite head 14 throughsteel stopper rod 13. A second electrical lead 18 connects to a graphiterod 19 situated in an opening 20 in the sidewall of the ladle andexposed to the ladle interior. The leads 17 and 18 are connected to acombination source of potential and a signal device for indicating achange in electrical character of a circuit such as a battery poweredvoltimeter 21.

Patented Jan. 24, 1967 When the ladle is used for transferring moltenmetal covered with slag as is conventional in the metal industries themeter 21 will give one reading so long as molten metal forms a part ofthe circuit between head 14 and rod 19. As soon as the slag reaches aposition where it forms the connection between head 14 and rod 19 a muchhigher resistance will occur providing a signal change on the voltimeter21. For example, with molten metal forming a part of the circuit areading of 0.1 to 0.3 ohm is obtained. As soon as the slag takes theplace of the molten metal as the circuit member the resistance will jumpto to 200 ohms or more depending upon the character of the slag. At thispoint the stopper rod is lowered shutting the nozzle and preventing slagfrom flowing from the ladle.

In the embodiment shown in FIGURE 2 we have illustrated a ladle 50,having a refractory lining 51, a nozzle 52 and a stopper rod 53 coveredby a refractory sleeve 54 and having a refractory head 55. Anelectrically powered operator 56 is mounted on the side of the ladle toraise and lower the stopper rod. This powered actuator may be anelectromagnet 57 having a moving core 58 or it may be a motor and driverod, or a solenoid operated air cylinder or any similar device. A pairof zirconium diboride rods 59 and 60 extend through openings in thesidewall of the ladle at a predetermined level above the bottom.Electrical leads 61 and 62 connect rods 59 and 60 to a source ofelectrical potential 63 and a signal device 64 such as a solenoid switchwhich actuates the operator 56. When the space between rods 59 and 60 isfilled with molten metal the actuator 56 holds the stopper rod 53 in theraised position with the nozzle open. When slag occupies the spacebetween the rods 59 and 60 the increased resistance opens the solenoid64 to cause actuator 56 to lower the rod into the nozzle cutting oif theflow from the ladle.

While we have illustrated and described certain preferred embodiments ofour invention in the foregoing specification, it will be apparent thatthis invention may be otherwise embodied within the scope of thefollowing claim.

We claim:

In a vessel for holding and transferring molten metal covered with slagor other material having a different conductivity than metal and havinga discharge nozzle and stopper rod for controlling the flow of metalthrough the nozzle, the improvement comprising a conductor membersituated in the ladle wall at a predetermined level adjacent thedischarge nozzle, a conductor stopper head on the stopper rod, anelectrical circuit connecting said conductive stopper head and saidconductor member, means for applying an electrical potential to saidcircuit, and signal means indicating a change in the electricalcharacteristics of said circuit.

References Cited by the Examiner UNITED STATES PATENTS 1,982,821 12/1924Marsclen et al. 252502 2,546,142 3/1951 Watson 252520 X FOREIGN PATENTS623,555 12/1935 Germany. 645,807 11/1950 Great Britain.

LOUIS R. PRINCE, Primary Examiner.

S. C. SWISHER, Assistant Examiner.

